Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Lochinvar main board repair

Fperkins
Fperkins Member Posts: 1
After 10 year my Knight WHN-155 failed to ignite. The only option was replacing the board which was rather costly and tricky to source. In looking at the board, the igniter fires from a “spark industries igniter transformer” which only has 3 solder points and would be easy to replace. Unfortunately I can’t source the part, but have contacted the manufacturer. Another option would be buying a used board in eBay which I can find similar models with the same component. My question is if there are any electronic repair sites/services/gurus who can take my old board and repair it? It seems like a waste to trash a $500+ board if only one part is defective.

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,987
    There was some information on this site just the other day about someone who repairs boards but I don't remember the post

    As a contractor or a service tech most wouldn't touch a job like that. Too much liability even installing a used board (I can here the Judge saying why didn't you by a new one)


    If it's you boiler and you can fix it somehow go ahead just know all the liability is on you. I don't have a problem with it
  • MaxMercy
    MaxMercy Member Posts: 289
    Fperkins said:

    After 10 year my Knight WHN-155 failed to ignite. The only option was replacing the board which was rather costly and tricky to source. In looking at the board, the igniter fires from a “spark industries igniter transformer” which only has 3 solder points and would be easy to replace.

    I work on a lot of expensive circuit boards for various industrial and automotive accounts with varying degrees of success. I Googled your numbers, and I come up with this board:

    imagehttps://www.macombgroup.com//ASSETS/IMAGES/ITEMS/DETAIL_PAGE/100167834.jpg

    https://www.macombgroup.com//ASSETS/IMAGES/ITEMS/DETAIL_PAGE/100167834.jpg


    If this is your board, this is a very sophisticated control board. Your ignition source may come from a transformer, but there is a driver transistor/mosfet/IGBT on the primary side that drives the transformer, most likely a gate driver IC, and that gate driver IC is commanded by the main processor based on what inputs it gets.

    If you have a working board, you can remove the transformer and do a resistance check. If it passes, you can then check it's inductance and finally a "ring" test. If it fails one of those, the transformer could/probably is bad. If it passes those tests, you have to go further back.

    Manufacturers do not publish schematics for these boards which makes troubleshooting so difficult. What we do is take the OEM numbers right off the chips (assuming the board builder didn't grind them down, which they sometimes do) and find the datasheet on line. The datasheet gives the breakdown of the IC's pins, and if we're lucky, a representative schematic of a "typical" usage of the IC. From this, we can often cobble together a crude wiring schematic. On a one-off repair, it's not worth the trouble in most cases. When one of my clients see two of the exact same symptom on a board, we give it a shot.



    ratio
  • ratio
    ratio Member Posts: 3,173
    @MaxMercy, can you share a ballpark of the costs involved? I think that might be eye-opening for those considering board-level repair.
  • bucksnort
    bucksnort Member Posts: 160
    I used these guys. They were local to me. Great service.
    https://www.circuitboardrepair.net
    psb75
  • MaxMercy
    MaxMercy Member Posts: 289
    ratio said:

    @MaxMercy, can you share a ballpark of the costs involved? I think that might be eye-opening for those considering board-level repair.

    Custom board work is not my trade, but I have industrial accounts that I do some custom board work as a professional courtesy. For instance, I have a few machine shop accounts that I've been repairing their machining center monitors for many years. If they have a problem with the electronic side of the machining center, they have to call the manufacturer and they will send an engineer to repair it. With airfare, lodging, parts, etc. the cost is quite high as you can imagine. For these jobs I will take a shot at the boards. Again, it's not a high percentage shot, but if I can identify the problem, the cost is a fraction of what they would pay, and it becomes a nice product if the problem is of the repeat variety.

    When my son's Mazda started skipping, we found bad plugs and a bad coil, but it still skipped. I pulled his computer apart and found a couple of shorted driver mosfets and burned gate resistors. I ordered the parts and it fixed the computer. I considered doing these but there are several places which do just these computers now and do them reasonably enough that it's not worth my time to set up an on-line business.

    In the case of this particular Lochinvar board, if this exact failure was routine and the only option was to replace it, I would take a shot at finding the cause of the problem if the symptom was always the same (in other words, not several different issues plaguing the same board).

    Trying to be more specific, the cost is dependent on how common the problem is and how to amortize the cost of time to write a repair procedure based on how many of these I will see in the future. I do some automotive clusters for a few local garages, and there is one Toyota cluster than I can repair now in literally 10 minutes after having done so many of them. The first one was billed time and material and it was several hours. The second one took half an hour, and I dropped the price on subsequent repairs. I charge these garages about 75% of what the on-line companies charge, but there is no shipping involved and they get them back the same day or within two hours if they need them that quickly, which is really nice compared to leaving a car disabled and on the lot for a week.